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Elhawary NA, AlJahdali IA, Abumansour IS, Azher ZA, Falemban AH, Madani WM, Alosaimi W, Alghamdi G, Sindi IA. Phenotypic variability to medication management: an update on fragile X syndrome. Hum Genomics 2023; 17:60. [PMID: 37420260 DOI: 10.1186/s40246-023-00507-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 07/03/2023] [Indexed: 07/09/2023] Open
Abstract
This review discusses the discovery, epidemiology, pathophysiology, genetic etiology, molecular diagnosis, and medication-based management of fragile X syndrome (FXS). It also highlights the syndrome's variable expressivity and common comorbid and overlapping conditions. FXS is an X-linked dominant disorder associated with a wide spectrum of clinical features, including but not limited to intellectual disability, autism spectrum disorder, language deficits, macroorchidism, seizures, and anxiety. Its prevalence in the general population is approximately 1 in 5000-7000 men and 1 in 4000-6000 women worldwide. FXS is associated with the fragile X messenger ribonucleoprotein 1 (FMR1) gene located at locus Xq27.3 and encodes the fragile X messenger ribonucleoprotein (FMRP). Most individuals with FXS have an FMR1 allele with > 200 CGG repeats (full mutation) and hypermethylation of the CpG island proximal to the repeats, which silences the gene's promoter. Some individuals have mosaicism in the size of the CGG repeats or in hypermethylation of the CpG island, both produce some FMRP and give rise to milder cognitive and behavioral deficits than in non-mosaic individuals with FXS. As in several monogenic disorders, modifier genes influence the penetrance of FMR1 mutations and FXS's variable expressivity by regulating the pathophysiological mechanisms related to the syndrome's behavioral features. Although there is no cure for FXS, prenatal molecular diagnostic testing is recommended to facilitate early diagnosis. Pharmacologic agents can reduce some behavioral features of FXS, and researchers are investigating whether gene editing can be used to demethylate the FMR1 promoter region to improve patient outcomes. Moreover, clustered regularly interspaced palindromic repeats (CRISPR)/Cas9 and developed nuclease defective Cas9 (dCas9) strategies have promised options of genome editing in gain-of-function mutations to rewrite new genetic information into a specified DNA site, are also being studied.
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Affiliation(s)
- Nasser A Elhawary
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia.
| | - Imad A AlJahdali
- Department of Community Medicine, College of Medicine, Umm Al-Qura University, Mecca, Saudi Arabia
| | - Iman S Abumansour
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia
| | - Zohor A Azher
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia
| | - Alaa H Falemban
- Department of Pharmacology and Toxicology, College of Medicine, Umm Al-Qura University, Mecca, 24382, Saudi Arabia
| | - Wefaq M Madani
- Department of Hematology and Immunology, Faculty of Medicine, Umm Al-Qura University, Mecca, Saudi Arabia
| | - Wafaa Alosaimi
- Department of Hematology, Maternity and Children Hospital, Mecca, Saudi Arabia
| | - Ghydda Alghamdi
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia
| | - Ikhlas A Sindi
- Department of Biology, Faculty of Science, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
- Preparatory Year Program, Batterjee Medical College, Jeddah, 21442, Saudi Arabia
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2
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Bartlett E, Archibald AD, Francis D, Ling L, Thomas R, Chandler G, Ward L, O'Farrell G, Pandelache A, Delatycki MB, Bennetts BH, Ho G, Fisk K, Baker EK, Amor DJ, Godler DE. Paternal retraction of a fragile X allele to normal size, showing normal function over two generations. Am J Med Genet A 2021; 188:304-309. [PMID: 34545686 DOI: 10.1002/ajmg.a.62500] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 08/09/2021] [Accepted: 08/18/2021] [Indexed: 11/09/2022]
Abstract
The FMR1 premutation (PM:55-199 CGG) is associated with fragile X-associated tremor/ataxia syndrome (FXTAS) and when maternally transmitted is at risk of expansion to a hypermethylated full mutation (FM: ≥ 200 CGG) that causes fragile X syndrome (FXS). We describe a maternally transmitted PM (77 CGG) that was passed to a son (103 CGG), and to a daughter (220-1822 CGG), who were affected with FXTAS and FXS, respectively. The male with the PM showed low-level mosaicism for normal size of 30 and 37 CGG. This male had two offspring: one female mosaic for PM and FM (56, 157, >200 CGG) and another with only a 37 CGG allele detected in multiple tissues, neither with a clinical phenotype. The female with the 37 CGG allele showed normal levels of FMR1 methylation and mRNA and passed this 37 CGG allele to one of her daughters, who was also unaffected. These findings show that post-zygotic paternal retraction can lead to low-level mosaicism for normal size alleles, with these normal alleles being functional when passed over two generations.
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Affiliation(s)
- Essra Bartlett
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Alison D Archibald
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.,Faculty of Medicine, Dentistry and Health Sciences, Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.,Bruce Lefroy Centre, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - David Francis
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Ling Ling
- Diagnosis and Development, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Rob Thomas
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Gabrielle Chandler
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Lisa Ward
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Gemma O'Farrell
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Alison Pandelache
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Martin B Delatycki
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.,Faculty of Medicine, Dentistry and Health Sciences, Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.,Bruce Lefroy Centre, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Bruce H Bennetts
- Sydney Genome Diagnostics-Molecular Genetics, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Discipline of Genetic Medicine, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Gladys Ho
- Sydney Genome Diagnostics-Molecular Genetics, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Discipline of Genetic Medicine, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Katrina Fisk
- Sydney Genome Diagnostics-Molecular Genetics, Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Emma K Baker
- Diagnosis and Development, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.,Faculty of Medicine, Dentistry and Health Sciences, Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.,School of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia
| | - David J Amor
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.,Faculty of Medicine, Dentistry and Health Sciences, Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.,Neurodisability and Rehabilitation, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - David E Godler
- Diagnosis and Development, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.,Faculty of Medicine, Dentistry and Health Sciences, Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
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Detection of Cryptic Fragile X Full Mutation Alleles by Southern Blot in a Female and Her Foetal DNA via Chorionic Villus Sampling, Complicated by Mosaicism for 45,X0/46,XX/47,XXX. Genes (Basel) 2021; 12:genes12060798. [PMID: 34073864 PMCID: PMC8225079 DOI: 10.3390/genes12060798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/08/2021] [Accepted: 05/18/2021] [Indexed: 11/23/2022] Open
Abstract
We describe a female with a 72 CGG FMR1 premutation (PM) (CGG 55–199) and family history of fragile X syndrome (FXS), referred for prenatal testing. The proband had a high risk of having an affected pregnancy with a full mutation allele (FM) (CGG > 200), that causes FXS through hypermethylation of the FMR1 promoter. The CGG sizing analysis in this study used AmplideX triplet repeat primed polymerase chain reaction (TP-PCR) and long-range methylation sensitive PCR (mPCR). These methods detected a 73 CGG PM allele in the proband’s blood, and a 164 CGG PM allele in her male cultured chorionic villus sample (CVS). In contrast, the Southern blot analysis showed mosaicism for: (i) a PM (71 CGG) and an FM (285–768 CGG) in the proband’s blood, and (ii) a PM (165 CGG) and an FM (408–625 CGG) in the male CVS. The FMR1 methylation analysis, using an EpiTYPER system in the proband, showed levels in the range observed for mosaic Turner syndrome. This was confirmed by molecular and cytogenetic karyotyping, identifying 45,X0/46,XX/47,XXX lines. In conclusion, this case highlights the importance of Southern blot in pre- and postnatal testing for presence of an FM, which was not detected using AmplideX TP-PCR or mPCR in the proband and her CVS.
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Kraan CM, Baker EK, Arpone M, Bui M, Ling L, Gamage D, Bretherton L, Rogers C, Field MJ, Wotton TL, Francis D, Hunter MF, Cohen J, Amor DJ, Godler DE. DNA Methylation at Birth Predicts Intellectual Functioning and Autism Features in Children with Fragile X Syndrome. Int J Mol Sci 2020; 21:ijms21207735. [PMID: 33086711 PMCID: PMC7589848 DOI: 10.3390/ijms21207735] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 10/15/2020] [Accepted: 10/16/2020] [Indexed: 12/12/2022] Open
Abstract
Fragile X syndrome (FXS) is a leading single-gene cause of intellectual disability (ID) with autism features. This study analysed diagnostic and prognostic utility of the Fragile X-Related Epigenetic Element 2 DNA methylation (FREE2m) assessed by Methylation Specific-Quantitative Melt Analysis and the EpiTYPER system, in retrospectively retrieved newborn blood spots (NBS) and newly created dried blood spots (DBS) from 65 children with FXS (~2–17 years). A further 168 NBS from infants from the general population were used to establish control reference ranges, in both sexes. FREE2m analysis showed sensitivity and specificity approaching 100%. In FXS males, NBS FREE2m strongly correlated with intellectual functioning and autism features, however associations were not as strong for FXS females. Fragile X mental retardation 1 gene (FMR1) mRNA levels in blood were correlated with FREE2m in both NBS and DBS, for both sexes. In females, DNAm was significantly increased at birth with a decrease in childhood. The findings support the use of FREE2m analysis in newborns for screening, diagnostic and prognostic testing in FXS.
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Affiliation(s)
- Claudine M Kraan
- Diagnosis and Development, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne VIC 3052, Australia; (C.M.K.); (E.K.B.); (M.A.); (L.L.); (D.G.); (L.B.); (D.J.A.)
- Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville VIC 3052, Australia
| | - Emma K Baker
- Diagnosis and Development, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne VIC 3052, Australia; (C.M.K.); (E.K.B.); (M.A.); (L.L.); (D.G.); (L.B.); (D.J.A.)
- Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville VIC 3052, Australia
- School of Psychology and Public Health, La Trobe University, Bundoora VIC 3086, Australia
| | - Marta Arpone
- Diagnosis and Development, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne VIC 3052, Australia; (C.M.K.); (E.K.B.); (M.A.); (L.L.); (D.G.); (L.B.); (D.J.A.)
- Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville VIC 3052, Australia
- Brain and Mind, Murdoch Children’s Research Institute, Royal Children’s Hospital, Parkville VIC 3052, Australia
| | - Minh Bui
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne VIC 3052, Australia;
| | - Ling Ling
- Diagnosis and Development, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne VIC 3052, Australia; (C.M.K.); (E.K.B.); (M.A.); (L.L.); (D.G.); (L.B.); (D.J.A.)
| | - Dinusha Gamage
- Diagnosis and Development, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne VIC 3052, Australia; (C.M.K.); (E.K.B.); (M.A.); (L.L.); (D.G.); (L.B.); (D.J.A.)
| | - Lesley Bretherton
- Diagnosis and Development, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne VIC 3052, Australia; (C.M.K.); (E.K.B.); (M.A.); (L.L.); (D.G.); (L.B.); (D.J.A.)
| | - Carolyn Rogers
- Genetics of Learning Disability Service (GOLD service), Hunter Genetics, Newcastle NSW 2298, Australia; (C.R.); (M.J.F.)
| | - Michael J Field
- Genetics of Learning Disability Service (GOLD service), Hunter Genetics, Newcastle NSW 2298, Australia; (C.R.); (M.J.F.)
| | - Tiffany L Wotton
- New South Wales Newborn Screening Program, Children’s Hospital at Westmead, Sydney NSW 2145, Australia;
| | - David Francis
- Victorian Clinical Genetics Services, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne VIC 3052, Australia;
| | - Matt F Hunter
- Monash Genetics, Monash Health, Clayton, VIC 3168, Australia;
| | - Jonathan Cohen
- Centre for Developmental Disability Health Victoria, Monash University, Doveton VIC 3177, Australia;
- Fragile X Alliance Inc., North Caulfield VIC 3161, Australia
| | - David J Amor
- Diagnosis and Development, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne VIC 3052, Australia; (C.M.K.); (E.K.B.); (M.A.); (L.L.); (D.G.); (L.B.); (D.J.A.)
- Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville VIC 3052, Australia
| | - David E Godler
- Diagnosis and Development, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne VIC 3052, Australia; (C.M.K.); (E.K.B.); (M.A.); (L.L.); (D.G.); (L.B.); (D.J.A.)
- Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville VIC 3052, Australia
- Correspondence: ; Tel.: +613-8341-6496
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Clinical and Molecular Differences between 4-Year-Old Monozygous Male Twins Mosaic for Normal, Premutation and Fragile X Full Mutation Alleles. Genes (Basel) 2019; 10:genes10040279. [PMID: 30959842 PMCID: PMC6523498 DOI: 10.3390/genes10040279] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 04/01/2019] [Accepted: 04/01/2019] [Indexed: 01/04/2023] Open
Abstract
This study describes monozygotic (MZ) male twins with fragile X syndrome (FXS), mosaic for normal size (NS: <44 CGGs), premutation (PM: 55–199 CGG) and full mutation (FM alleles ≥ 200) alleles, with autism. At 4 years of age chromosomal microarray confirmed monozygosity with both twins showing an XY sex complement. Normal size (30 CGG), PM (99 CGG) and FM (388–1632 CGGs) alleles were detected in Twin 1 (T1) by standard polymerase chain reaction (PCR) and Southern blot testing, while only PM (99 CGG) and FM (672–1025) alleles were identified in Twin 2 (T2). At ~5 years, T2 had greater intellectual impairments with a full scale IQ (FSIQ) of 55 and verbal IQ (VIQ) of 59, compared to FSIQ of 62 and VIQ of 78 for T1. This was consistent with the quantitative FMR1 methylation testing, revealing 10% higher methylation at 80% for T2; suggesting that less active unmethylated alleles were present in T2 as compared to T1. AmplideX methylation PCR also identified partial methylation, including an unmethylated NS allele in T2, undetected by standard testing. In conclusion, this report demonstrates significant differences in intellectual functioning between the MZ twins mosaic for NS, PM and FM alleles with partial FMR1 promoter methylation.
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Bacrot S, Monnot S, Haddad G, Barcia G, Rachid M, Boisson M, Pasquier N, Rondeau S, Munnich A, Steffann J, Bonnefont JP, Raynaud M. Prenatal diagnosis of fragile X syndrome: Small meiotic recombination events at the FMR1 locus. Prenat Diagn 2019; 39:388-393. [PMID: 30779209 DOI: 10.1002/pd.5439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 02/11/2019] [Accepted: 02/16/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Séverine Bacrot
- Université Paris Descartes - Sorbonne Paris Cite, Institut Imagine UMR1163, Fédération de Génétique médicale, Hôpital universitaire Necker-Enfants Malades, AP-HP, Paris, France
| | - Sophie Monnot
- Université Paris Descartes - Sorbonne Paris Cite, Institut Imagine UMR1163, Fédération de Génétique médicale, Hôpital universitaire Necker-Enfants Malades, AP-HP, Paris, France
| | - Georges Haddad
- Service de gynécologie obstétrique, Centre hospitalier de Blois, Blois, France
| | - Giulia Barcia
- Université Paris Descartes - Sorbonne Paris Cite, Institut Imagine UMR1163, Fédération de Génétique médicale, Hôpital universitaire Necker-Enfants Malades, AP-HP, Paris, France
| | - Myriam Rachid
- Université Paris Descartes - Sorbonne Paris Cite, Institut Imagine UMR1163, Fédération de Génétique médicale, Hôpital universitaire Necker-Enfants Malades, AP-HP, Paris, France
| | - Marie Boisson
- Université Paris Descartes - Sorbonne Paris Cite, Institut Imagine UMR1163, Fédération de Génétique médicale, Hôpital universitaire Necker-Enfants Malades, AP-HP, Paris, France
| | - Nathalie Pasquier
- Service de Génétique, CHRU de Tours, UMR 1253, iBrain, Université de Tours, Inserm, Tours, France
| | - Sophie Rondeau
- Université Paris Descartes - Sorbonne Paris Cite, Institut Imagine UMR1163, Fédération de Génétique médicale, Hôpital universitaire Necker-Enfants Malades, AP-HP, Paris, France
| | - Arnold Munnich
- Université Paris Descartes - Sorbonne Paris Cite, Institut Imagine UMR1163, Fédération de Génétique médicale, Hôpital universitaire Necker-Enfants Malades, AP-HP, Paris, France
| | - Julie Steffann
- Université Paris Descartes - Sorbonne Paris Cite, Institut Imagine UMR1163, Fédération de Génétique médicale, Hôpital universitaire Necker-Enfants Malades, AP-HP, Paris, France
| | - Jean-Paul Bonnefont
- Université Paris Descartes - Sorbonne Paris Cite, Institut Imagine UMR1163, Fédération de Génétique médicale, Hôpital universitaire Necker-Enfants Malades, AP-HP, Paris, France
| | - Martine Raynaud
- Service de Génétique, CHRU de Tours, UMR 1253, iBrain, Université de Tours, Inserm, Tours, France
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Prenatal Diagnosis of Fragile X Syndrome in a Twin Pregnancy Complicated by a Complete Retraction. Genes (Basel) 2018; 9:genes9060287. [PMID: 29880767 PMCID: PMC6027392 DOI: 10.3390/genes9060287] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 05/31/2018] [Accepted: 06/04/2018] [Indexed: 01/09/2023] Open
Abstract
Fragile X syndrome (FXS) is usually associated with a CGG repeat expansion >200 repeats within the FMR1 gene, known as a full mutation (FM). FM alleles produce abnormal methylation of the FMR1 promoter with reduction or silencing of FMR1 gene expression. Furthermore, premutation (PM: 55–199 CGGs) and full mutation alleles usually expand in size when maternally transmitted to progeny. This study describes a PM allele carried by the mother decreasing to a normal sized allele in a male from a dichorionic diamniotic (DCDA) twin pregnancy, with the female twin inheriting FM (200–790 CGGs), PM (130 CGGs) and normal-sized (39 CGGs) alleles. Further evidence of instability of the maternal PM allele was shown by a male proband (older brother) mosaic for PM (CGG 78 and 150 CGGs) and FM (200–813 CGGs), and a high level of FMR1 promoter methylation, between 50 and 70%, in multiple tissues. The fully-retracted, normal-sized allele was identified by PCR CGG sizing in the male twin, with no evidence of a FM allele identified using Southern blot analysis in multiple tissues collected postnatally and prenatally. Consistent with this, prenatal PCR sizing (35 CGGs) showed inconsistent inheritance of the maternal normal allele (30 CGGs), with single-nucleotide polymorphism (SNP) linkage analysis confirming that the abnormal FMR1 chromosome had been inherited from the mother’s PM chromosome. Importantly, the male twin showed no significant hypermethylation of the FMR1 promoter in all pre and postnatal tissues tested, as well as normal levels of FMR1 mRNA in blood. In summary, this report demonstrates the first postnatal follow up of a prenatal case in which FMR1 mRNA levels were approaching normal, with normal levels of FMR1 promoter methylation and normal CGG size in multiple pre and postnatally collected tissues.
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Arpone M, Baker EK, Bretherton L, Bui M, Li X, Whitaker S, Dissanayake C, Cohen J, Hickerton C, Rogers C, Field M, Elliott J, Aliaga SM, Ling L, Francis D, Hearps SJC, Hunter MF, Amor DJ, Godler DE. Intragenic DNA methylation in buccal epithelial cells and intellectual functioning in a paediatric cohort of males with fragile X. Sci Rep 2018; 8:3644. [PMID: 29483611 PMCID: PMC5827525 DOI: 10.1038/s41598-018-21990-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 02/12/2018] [Indexed: 01/05/2023] Open
Abstract
Increased intragenic DNA methylation of the Fragile X Related Epigenetic Element 2 (FREE2) in blood has been correlated with lower intellectual functioning in females with fragile X syndrome (FXS). This study explored these relationships in a paediatric cohort of males with FXS using Buccal Epithelial Cells (BEC). BEC were collected from 25 males with FXS, aged 3 to 17 years and 19 age-matched male controls without FXS. Methylation of 9 CpG sites within the FREE2 region was examined using the EpiTYPER approach. Full Scale IQ (FSIQ) scores of males with FXS were corrected for floor effect using the Whitaker and Gordon (WG) extrapolation method. Compared to controls, children with FXS had significant higher methylation levels for all CpG sites examined (p < 3.3 × 10−7), and within the FXS group, lower FSIQ (WG corrected) was associated with higher levels of DNA methylation, with the strongest relationship found for CpG sites within FMR1 intron 1 (p < 5.6 × 10−5). Applying the WG method to the FXS cohort unmasked significant epi-genotype-phenotype relationships. These results extend previous evidence in blood to BEC and demonstrate FREE2 DNA methylation to be a sensitive epigenetic biomarker significantly associated with the variability in intellectual functioning in FXS.
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Affiliation(s)
- Marta Arpone
- Faculty of Medicine, Dentistry and Health Sciences, Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia. .,Cyto-Molecular Diagnostics Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia. .,Child Neuropsychology, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia.
| | - Emma K Baker
- Cyto-Molecular Diagnostics Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia
| | - Lesley Bretherton
- Faculty of Medicine, Dentistry and Health Sciences, Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.,Child Neuropsychology, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia.,Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Minh Bui
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, VIC, Australia
| | - Xin Li
- Cyto-Molecular Diagnostics Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia
| | - Simon Whitaker
- School of Human and Health Science, University of Huddersfield, Queensgate, Huddersfield, United Kingdom
| | - Cheryl Dissanayake
- Olga Tennison Autism Research Centre, La Trobe University, Melbourne, VIC, Australia
| | - Jonathan Cohen
- Fragile X Alliance Inc, North Caulfield, VIC, Australia and Centre for Developmental Disability Health Victoria, Monash University, Dandenong, VIC, Australia
| | - Chriselle Hickerton
- Cyto-Molecular Diagnostics Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia
| | - Carolyn Rogers
- Genetics of Learning Disability Service (GOLD service), Hunter Genetics, Newcastle, NSW, Australia
| | - Mike Field
- Genetics of Learning Disability Service (GOLD service), Hunter Genetics, Newcastle, NSW, Australia
| | - Justine Elliott
- Victorian Clinical Genetics Services and Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia
| | - Solange M Aliaga
- Faculty of Medicine, Dentistry and Health Sciences, Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.,Cyto-Molecular Diagnostics Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia.,Centre for Diagnosis and Treatment of Fragile X Syndrome, INTA University of Chile, Santiago, Chile
| | - Ling Ling
- Cyto-Molecular Diagnostics Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia
| | - David Francis
- Victorian Clinical Genetics Services and Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia
| | - Stephen J C Hearps
- Child Neuropsychology, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia
| | - Matthew F Hunter
- Monash Genetics, Monash Health, Melbourne, VIC, Australia and Department of Paediatrics, Monash University, Melbourne, VIC, Australia
| | - David J Amor
- Faculty of Medicine, Dentistry and Health Sciences, Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.,Victorian Clinical Genetics Services and Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia
| | - David E Godler
- Faculty of Medicine, Dentistry and Health Sciences, Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.,Cyto-Molecular Diagnostics Research, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC, Australia
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Ciaccio C, Fontana L, Milani D, Tabano S, Miozzo M, Esposito S. Fragile X syndrome: a review of clinical and molecular diagnoses. Ital J Pediatr 2017; 43:39. [PMID: 28420439 PMCID: PMC5395755 DOI: 10.1186/s13052-017-0355-y] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 04/07/2017] [Indexed: 12/24/2022] Open
Abstract
Background Fragile X Syndrome (FXS) is the second cause of intellectual disability after Down syndrome and the most prevalent cause of intellectual disability in males, affecting 1:5000–7000 men and 1:4000–6000 women. It is caused by an alteration of the FMR1 gene, which maps at the Xq27.3 band: more than 99% of individuals have a CGG expansion (>200 triplets) in the 5′ UTR of the gene, and FMR1 mutations and duplication/deletion are responsible for the remaining (<1%) molecular diagnoses of FXS. The aim of this review was to gather the current clinical and molecular knowledge about FXS to provide clinicians with a tool to guide the initial assessment and follow-up of FXS and to offer to laboratory workers and researchers an update about the current diagnostic procedures. Discussion FXS is a well-known condition; however, most of the studies thus far have focused on neuropsychiatric features. Unfortunately, some of the available studies have limitations, such as the paucity of patients enrolled or bias due to the collection of the data in a single-country population, which may be not representative of the average global FXS population. In recent years, insight into the adult presentation of the disease has progressively increased. Pharmacological treatment of FXS is essentially symptom based, but the growing understanding of the molecular and biological mechanisms of the disease are paving the way to targeted therapy, which may reverse the effects of FMRP deficiency and be a real cure for the disease itself, not just its symptoms. Conclusions The clinical spectrum of FXS is wide, presenting not only as an isolated intellectual disability but as a multi-systemic condition, involving predominantly the central nervous system but potentially affecting any apparatus. Given the relative high frequency of the condition and its complex clinical management, FXS appears to have an important economic and social burden.
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Affiliation(s)
- Claudia Ciaccio
- Pediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via Commenda 9, 20122, Milan, Italy
| | - Laura Fontana
- Division of Pathology, Department of Pathophysiology and Transplantation, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Donatella Milani
- Pediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via Commenda 9, 20122, Milan, Italy
| | - Silvia Tabano
- Division of Pathology, Department of Pathophysiology and Transplantation, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Monica Miozzo
- Division of Pathology, Department of Pathophysiology and Transplantation, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Susanna Esposito
- Pediatric Clinic, Department of Surgical and Biomedical Sciences, Università degli Studi di Perugia, Piazza Lucio Severi 1, Loc. S. Andrea delle Fratte, 06132, Perugia, Italy.
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